Controlled header lowering on an agricultural harvester

ABSTRACT

A header assembly for an agricultural harvesting machine comprises a first frame assembly, a second frame assembly that supports a cutter, and is pivotable relative to the first frame assembly, a float cylinder coupled between the first frame assembly and the second frame assembly, an accumulator, and fluidic circuitry that fluidically couples the accumulator to the float cylinder. The fluidic circuitry is configured to provide a first flow of pressurized fluid under pressure to the float cylinder, so the float cylinder exerts a float force on the second frame assembly, and based on a control input that corresponds to a lowering operation of the header assembly, provide a restricted flow of fluid, that is restricted relative to the first flow, between the float cylinder and the accumulator.

FIELD OF THE DESCRIPTION

This description generally relates to agricultural equipment. Morespecifically, but not by limitation, the present description relates toa system for applying float pressure on the header of an agriculturalharvester.

BACKGROUND

There is a wide variety of different types of agricultural equipment.Some such equipment includes agricultural harvesters.

It is common for agricultural harvesters (such as combine harvesters,forage harvesters, windrowers, etc.) to have a header. On an examplecombine, the header is attached to a feeder house by an attachmentframe. The header has a main frame that supports a cutter bar and areel. The main frame is movable relative to the attachment frame. As theharvester travels, the header engages crop, severs it and transfers thecrop into the harvester for further processing.

One type of cutting platform for a combine is referred to as a draperplatform, which utilizes a flat, wide belt, referred to as a draper ordraper belt to convey crop material. The arrangement and number of beltsvary among platforms. One style of draper platform has two side beltsthat convey crop material longitudinally, to the center of the platform,where a center feed belt moves the crop material laterally into thefeeder house. Each belt is wrapped around a pair of rollers, one being adrive roller and the other being an idler roller.

The discussion above is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter.

SUMMARY

An example header assembly for an agricultural harvesting machinecomprises a first frame assembly, a second frame assembly that supportsa cutter, and is pivotable relative to the first frame assembly, a floatcylinder coupled between the first frame assembly and the second frameassembly, an accumulator, and fluidic circuitry that fluidically couplesthe accumulator to the float cylinder. The fluidic circuitry isconfigured to provide a first flow of pressurized fluid under pressureto the float cylinder, so the float cylinder exerts a float force on thesecond frame assembly, and based on a control input that corresponds toa lowering operation of the header assembly, provide a restricted flowof fluid, that is restricted relative to the first flow, between thefloat cylinder and the accumulator.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter. The claimed subject matter is not limited to implementationsthat solve any or all disadvantages noted in the background.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial pictorial, partial schematic view of one example ofa combine harvester.

FIG. 2 shows one example of a float force assembly with an attachmentframe and main frame in a first position relative to one another.

FIG. 3 illustrates an example header for a combine harvester.

FIG. 4 is a schematic diagram of one example of a hydraulic circuit fora float force assembly.

FIG. 5 is a flow diagram illustrating an example method of operation ofthe hydraulic circuit illustrated in FIG. 4.

FIGS. 6 and 7 are schematic diagrams of the hydraulic circuit shown inFIG. 4, during the example method of operation shown in the FIG. 5.

DETAILED DESCRIPTION

Some harvester headers have a main frame that supports the headerstructure. Example agricultural harvesters include, but are not limitedto, combine harvesters, forage harvesters, and windrowers, etc. The mainframe is movable relative to a traction unit (such as a combineharvester) by a positioning actuator so the header can be positioned ata desired height relative to the ground (e.g., in order to float abovethe ground, and sometimes in order to set a tilt angle of the header aswell).

It is believed that improved harvesting performance can be achieved whenthe header generally follows the surface of the ground, so that itmaintains roughly the same distance above the ground throughout theharvesting operation.

In order to achieve better ground following performance, some harvestersare configured with a float assembly that applies a float force to theheader and/or to portions of the header, such as wing sections in thecase of a winged draper. The float force is a lifting force (e.g., tothe main frame relative to the traction unit) oriented to maintain theheader (or portions thereof) at the given distance above the ground.This allows the header to respond to changing ground levels and tocontact with obstacles to better follow the ground.

The header often has ground engaging elements which provide a groundreference input to the header. Therefore, if the ground underneath theheader falls, the header is normally weighted sufficiently to overcomethe float force so the main frame drops to follow the ground downward.If the ground under the header rises, then the ground engaging elementsact to aid the float force in lifting the header (e.g., lifting the mainframe) to follow the ground upward.

It is also not uncommon for there to be obstacles (such as dirt, rootballs, rocks, or other obstacles) in the path of the harvester. When theheader (or the ground engaging elements) contact an obstacle, this canimpart a lifting force (or pulse) on the header as well. The float forceallows the header to respond to the upwardly directed force, by risingup, and then settling back to its original position relative to theground.

In some systems, a float cylinder is hydraulically coupled to anaccumulator. The accumulator provides hydraulic fluid under pressure tothe float cylinder, which, in turn, provides the lifting force. When anupwardly directed force is imparted on the header (such as when theheader, or a ground engaging element of the header, strikes an obstacleon the ground) the header rises, assisted by the float force, and thefloat cylinder draws hydraulic fluid out of the accumulator. The headerthen falls back to its original position, because the weight of theheader overcomes the upwardly directed float force (e.g., pressure inthe accumulator).

FIG. 1 is a partial pictorial, partial schematic, illustration of anagricultural machine 100, in an example where machine 100 is a combineharvester (also referred to as combine 100 or machine 100). It can beseen in FIG. 1 that combine 100 illustratively includes an operatorcompartment 101, which can have a variety of different operatorinterface mechanisms, for controlling combine 100. Combine 100 includesa set of front end equipment, forming a cutting platform 102, thatincludes a header 104 having a cutter generally indicated at 106. It canalso include a feeder house 108, a feed accelerator 109, and a threshergenerally indicated at 111. Thresher 111 illustratively includes athreshing rotor 112 and a set of concaves 114. Further, combine 100 caninclude a separator 116 that includes a separator rotor. Combine 100 caninclude a cleaning subsystem (or cleaning shoe) 118 that, itself, caninclude a cleaning fan 120, chaffer 122 and sieve 124. The materialhandling subsystem in combine 100 can include (in addition to a feederhouse 108 and feed accelerator 109) discharge beater 126, tailingselevator 128, clean grain elevator 130 (that moves clean grain intoclean grain tank 132) as well as unloading auger 134 and spout 136.Combine 100 can further include a residue subsystem 138 that can includechopper 140 and spreader 142. Combine 100 can also have a propulsionsubsystem that includes an engine (or other power source) that drivesground engaging wheels 144 or tracks, etc. It will be noted that combine100 may also have more than one of any of the subsystems mentioned above(such as left and right cleaning shoes, separators, etc.).

Combine 100 can be equipped with removable cutting platforms that aredesigned for particular crops. One example, sometimes called a grainplatform, is equipped with a reciprocating knife cutter bar, andfeatures a revolving reel with metal or plastic teeth to cause the cutcrop to fall into the auger once it is cut. Another example includes acutter bar that can flex over contours and ridges to cut crops such assoybeans that have pods close to the ground. Some headers designed forwheat, or other similar crops, include draper headers, and use a fabricor rubber apron instead of a cross auger. Often, a draper platformincludes one or more draper belts that move severed material, that isharvested from an agricultural field, into a header of the agriculturalharvesting machine. In one example, this includes one or more draperbelts on each side of the header configured to receive and move severedmaterial to a center section of the agricultural header.

As shown in FIG. 1, header 104 has a main frame 107 and an attachmentframe 110. Header 104 is attached to feeder house 108 by an attachmentmechanism on attachment frame 110 that cooperates with an attachmentmechanism on feeder house 108. Main frame 107 supports cutter 106 andreel 105 and is movable relative to attachment frame 110. In oneexample, main frame 107 and attachment frame 110 can be raised andlowered together to set a height of cutter 106 above the ground overwhich combine 100 is traveling. In another example, main frame 107 canbe tilted relative to attachment frame 110 to adjust a tilt angle withwhich cutter 106 engages the crop. Also, in one example, main frame 107can be rotated or otherwise movable relative to attachment frame 110 inorder to improve ground following performance. The movement of mainframe 107 together with attachment frame 110 can be driven by actuators(such as hydraulic actuators) based on operator inputs or automatedinputs.

In operation, and by way of overview, the height of header 104 is setand combine 100 illustratively moves through a field in the directionindicated by arrow 146. As it moves, header 104 engages the crop to beharvested and gathers it toward cutter 106. After it is cut, the cropcan be engaged by reel 105 that moves the crop to feeding tracks. Thefeeding tracks move the crop to the center of the header 104 and thenthrough a center feeding track in feeder house 108 toward feedaccelerator 109, which accelerates the crop into thresher 111. The cropis threshed by rotor 112 rotating the crop against concaves 114. Thethreshed crop is moved by a separator rotor in separator 116 where someof the residue is moved by discharge beater 126 toward a residuesubsystem. It can be chopped by a residue chopper 140 and spread on thefield by spreader 142. In other implementations, the residue is simplydropped in a windrow, instead of being chopped and spread.

FIG. 1 also shows that, in one example, combine 100 can include groundspeed sensor 147, one or more separator loss sensors 148, a clean graincamera 150, and one or more cleaning shoe loss sensors 152. Ground speedsensor 147 illustratively senses the travel speed of combine 100 overthe ground. This can be done by sensing the speed of rotation of thewheels, the drive shaft, the axle, or other components. The travel speedcan also be sensed by a positioning system, such as a global positioningsystem (GPS), a dead reckoning system, a LORAN system, or a wide varietyof other systems or sensors that provide an indication of travel speed.

As combine 100 moves in the direction indicated by arrow 146, it may bethat the ground under header 104 contains obstacles or is uneven. Header104 is thus provided with ground engaging elements (such as shoes orgauge wheels) that engage the surface of the ground over which combine100 is traveling. Combine 100 is also provided with float force assembly170. Float force assembly 170 is shown schematically in FIG. 1, andapplies a float force, that is illustratively a lifting force that actsagainst gravity, biasing main frame 107 of header 104 in an upwarddirection relative to attachment frame 110. Therefore, as the groundunder header 104 rises, the ground engaging elements on header 104engage the rising ground surface and push upwardly on main frame 107.The float force applied by float force assembly 170 assists in raisingheader 104 up to follow the rising ground surface. In areas where theground falls off, the weight of header 104 overcomes the float force sothat it descends to its ground following set point or to a point wherethe ground engaging elements again engage the surface of the ground.

Similarly, if header 104, or one of the ground engaging elements onheader 104, engage an obstacle (such as by striking a stone, a clump ofdirt, a root ball, etc.), this impact may impart an upwardly directedforce on header 104 as well. This upwardly directed force will berelatively sharp and of short duration (or pulsed). Again, as when theground rises under header 104, the float force applied by float forceassembly 170 assists in raising header 104 up, in response to theupwardly directed force imparted by the impact with the obstacle. Thisacts to absorb some of the impact and allow the header 104 to rise abovethe obstacle. The weight of the header 104 then causes it to act againstthe float force and return to its ground following position.

FIG. 2 shows one example of a portion of header 104 with a float forceassembly 170, that applies a float force, to header 104. In the exampleshown in FIG. 2, some elements are similar to those shown in FIG. 1, andthey are similarly numbered.

FIG. 2 shows that main frame 107, which supports cutter 106 and reel 105(not shown in FIG. 2) is at a first position relative to attachmentframe 110. Attachment frame 110 illustratively includes an attachmentmechanism (not shown) that attaches to a corresponding attachmentmechanism on feeder house 108. The vertical movement of main frame 107relative to attachment frame 110 is illustratively driven by groundengaging elements, such as gauge wheels, shoes or skis (not shown) whichact to raise and lower main frame 107 relative to attachment frame 110as the ground over which the ground engaging elements move rises andfalls, respectively. As mentioned above, vertical movement can also bedriven by the impact of one of the ground engaging elements or theheader 104 with an obstacle. In another example, main frame 107 can alsobe tilted relative to attachment frame 110 by a tilt actuator (also notshown).

In the example illustrated in FIG. 2, a set of control arms 172 and 174are pivotally connected to attachment frame 110 at pivot points 176 and178, and are pivotally attached to main frame 107 at pivot points 180and 182, respectively. Control arms 172 and 174 control the path ofmovement of main frame 107 relative to attachment frame 110 when theposition of main frame 107 relative to attachment frame 110 changes tofollow the ground. This is just one example of an arrangement forcontrolling the path of movement.

Float force assembly 170 illustratively includes cylinder 184 that ispivotally connected to attachment frame 110 at pivot point 187, and thatis pivotally attached to main frame 107 at pivot point 189. Hydrauliccylinder 184 has a rod portion 186 reciprocally mounted within cylinderportion 188. Assembly 170 also illustratively includes an accumulator190. Accumulator 190 is shown schematically in FIG. 2 and is shownattached to cylinder 184, through a hydraulic circuit 191. It will beappreciated that, in one example, it can be internal to hydrauliccylinder 184. In another example, accumulator 190 and circuit 191 can beseparate from hydraulic cylinder 184 and fluidically coupled tohydraulic cylinder 184. In one example, there are at least two floatforce assemblies 170, disposed in spaced relation to one another acrossthe header 104. This is just an example.

Accumulator 190 can take a wide variety of different forms. Forinstance, the accumulator 190 can include a diaphragm or other pressuretransmitting mechanism. The diaphragm can have one side in fluidcommunication with the rod end of cylinder 184 and has a compressiblefluid or a compressible gas disposed on its other side. When rod portion186 is extended further out cylinder portion 188, the pressure increasesin the rod end of cylinder 184, and the diaphragm compresses thecompressible medium in accumulator 190, thus increasing the pressure inaccumulator 190. When rod portion 186 is further retracted into ofcylinder portion 188, then the pressure in the base end of cylinder 184is reduced, and the compressible medium expands, pushing against thediaphragm (or other movable member) so that the pressure in accumulator190 is reduced and hydraulic fluid is drawn from the accumulator 190into the rod end of the cylinder.

FIG. 3 illustrates an example cutting platform 200, in the form of adraper (also referred to as draper 200), that can be attached to afeeder house of a combine. Cutting platform 200 generally includes aplurality of platform sections 202, 204 and 206, a cutterbar assembly208 and a reel assembly 210. In the example shown, platform section 202comprises a center section (also referred to as center section or frame202), platform section 204 comprises a first wing platform section (alsoreferred to as first wing 204), and platform section 206 comprises asecond wing platform section (also referred to as second wing 206). Inone example, center section 202 comprises, or is attached to, a headermain frame 212 (such as main frame 107) and the first and second wings204 and 206 are movably attached to left and right sides, respectively,of center section 202. For example, main frame 212 can be attached to anattachment frame (not shown in FIG. 3) through a float cylinder (notshown in FIG. 3), where the attachment frame is attached to feeder house214. Although shown with three platform sections, cutting platform 200may be configured with more or less platform sections, depending uponthe particular application.

Each of the first and second wings 204 and 206 generally includes aframe 216, a plurality of arms coupled with the respective frame 216, acutterbar 218 carried by the outboard ends of the arms, an endless belt220, and a plurality of belt guides (not shown in FIG. 3). Eachcutterbar 218 includes a plurality of knives carried by a bar (notspecifically shown). The particular type of knife can vary, such as asingle blade knife or a double blade knife. The bar is formed from ametal which is flexible to an extent allowing a desired degree offlexure across the width of cutting platform 200.

The frame 216 of first wing platform section 204 and second wingplatform section 206 are each pivotally coupled with center platformsection 202, such that the outboard ends of first wing platform section204 and second wing platform section 206 can move up and downindependent from center platform section 202. To that end, a liftcylinder is coupled between the frame of the combine and feeder house214 and lifts the entire cutting platform 200. Tilt cylinders arecoupled between the respective frames 216 of the first and second wings204 and 206, and operate to pivotably move first and second wingsrelative to center platform section 202. The tilt cylindersillustratively operate to raise first and second wings 204 and 206 to atransport mode.

Each wing section 204 and 206 includes a respective float force assemblythat applies a float force to the wing section that assists in raisingthe wing section up, relative to the center section 202, for instance inresponse to an upwardly directed force imparted by an impact with anobstacle. This acts to absorb some of the impact and allow the wing torise above the obstacle. The weight of the wing then acts against thefloat force and to return the wing to its ground following position. Inthe illustrated example, a first float force assembly 222 includes afloat cylinder 224 that is attached to the frame 216 of first wing 204.Similarly, a second float force assembly 226 includes a float cylinder228 that is attached to the frame 216 of second wing 206. Each floatcylinder 224 and 228 is fluidically coupled to a respective accumulatorby hydraulic (or other fluid) circuitry.

In one example system, the hydraulic circuit allows hydraulic fluid tofreely flow through a hydraulic conduit between the float cylinder andthe accumulator. This can present difficulties. For instance, when thetraction unit lowers the header onto uneven ground (such as the crest ofa hill), one or both of the wings 204 and 206 may be positioned asubstantial distance from the ground when the center platform 202engages the ground at the crest. In this case, the wing(s) (e.g., whenreleased or unlocked from the center platform 202) can fall quicklyuntil they hit the ground with a large impact, which can be perceived bythe operator of the traction unit and/or can damage the header ortraction unit.

For sake of further illustration, assume a combine makes a first passacross a substantially level terrain. When the combine reaches the endof the pass, the wings are locked in their current position as theheader is raised for a turn to a make a subsequent parallel (or other)pass on the terrain. However, this subsequent pass may be onsubstantially uneven ground, such that when the header is lowered andthe wings are unlocked, one or more of the wings fall quickly until theyimpact the ground.

However, if the float force on the wings is too high during a harvestingoperation in which the header is following the ground, the wings willnot fall fast enough after striking an obstacle (or when the groundfalls away) to follow the ground, which results in missed crop and poorharvesting performance.

FIG. 4 is a schematic diagram of one example of a hydraulic circuit 400of a float force assembly 402 for a header. For sake of illustration,but not by limitation, hydraulic circuit 400 and float force assembly402 will be described in the context of float force assembly 222 (or226) of draper 200. However, circuit 400 and assembly 402 can beutilized in other types of header platforms as well.

Hydraulic circuit 400 is configured to provide a damped float responseduring a lowering operation of a frame assembly 403 of the headerrelative to another frame assembly 405. In the present example, frameassembly 403 comprises wing section 204 (or 206) and frame assembly 405comprises center section 202 to which wing section 204 is pivotableconnected. In one example, each wing section 204 and 206 can have aseparate float force assembly 402 for providing a float force on therespective wing section 204, 206 relative to center section 202.

Hydraulic circuit 400 is configured to provide a damped float responseduring a lowering operation of frame assembly 403. For sake ofillustration, and as discussed in further detail below, when wingsection 204 is released from a locked position relative to centerplatform 202, hydraulic circuit 400 is configured to provide restrictedhydraulic fluid flow to damp or slow the rate at which wing section 204is lowered to the ground, thus reducing the impact wing section 204 haswith the ground.

FIG. 4 shows that an accumulator 404 is hydraulically coupled throughone or more hydraulic fluid conduits, defined for example by tubes 406and tube 408. Tube 406 and the defined conduit may be referred tohereinafter as conduit 406 and the tube and defined conduit 408 may bereferred to hereinafter as conduit 408. One example accumulator isdescribed above with respect to accumulator 190.

Hydraulic circuit 400 also includes one or more valve mechanismsconfigured to control the flow of hydraulic fluid through conduits 406and 408 between accumulator 404 and a float cylinder 410. One examplefloat cylinder is described above with respect to float cylinder 184.

Hydraulic circuit 400 includes a first control valve 411 and a secondcontrol valve 412. Control valve 411 is movable between an open position(illustrated in FIG. 4) that allows fluid flow therethrough and a closedposition that blocks fluid flow. Accordingly, control valve 411 isactuatable to a closed position (moved to the left in FIG. 4) whichhydraulically isolates float cylinder 410 from accumulator 404, whichhas the affect of locking float cylinder 410, and thus the position offrame assembly 403 relative to frame assembly 405.

A rod 414 of float cylinder 410 is connected to frame assembly 403 andan end of cylinder 410 is hydraulically coupled to accumulator 404through hydraulic circuitry 400. The base end of cylinder 410 isconnected to frame assembly 405.

Control valve 412 is also disposed along the fluid path formed by theconduit(s) between accumulator 404 and float cylinder 410 and isconfigured to selectively control the flow of hydraulic fluid betweenaccumulator 404 and float cylinder 410. As discussed in further detailbelow, control valve 412 is operable to selectively configure hydrauliccircuit 400 to provide a first, substantially unrestricted flow betweenfloat cylinder 410 and accumulator 404, and to provide a second,restricted flow (that is restricted relative to the first flow) betweenfloat cylinder 410 and accumulator 404.

Briefly, during a normal, non-lifted operation (i.e., ground-engagingelements of frame assemblies 403 and 405 are on the ground), valves 411and 412 are in an open position (i.e., in FIG. 4, control valve 411 ismoved to the right and control valve 412 is moved to the left), so thatthe hydraulic fluid can pass through hydraulic circuit 400 substantiallyunrestricted. As such, when frame assembly 403 (or its ground engagingelements) receives an impact from an obstacle, there will be an upwardlydirected force imparted on the rod 414 of cylinder 410. This will causerod 414 to retract into cylinder 410, and thus drive hydraulic fluidfrom the base end of cylinder 410 through hydraulic circuit 400 intoaccumulator 404.

Hydraulic circuit 400 can also be selectively connected to a hydraulicsource 416 on the header and/or traction unit through a control valve418. During operation, hydraulic source 416 is generally isolated fromhydraulic circuit 400 by control valve 418 being in the closed positionillustrated in FIG. 4. Hydraulic source 416 is selectively couplable tohydraulic circuit 400 by opening control valve 418 to a position thatcontrols the flow of hydraulic fluid from (or to) hydraulic source 416.Control valve 418 includes a pressure control valve 420 that, whenplaced in-line between hydraulic source 416 and hydraulic circuit 400,controls the hydraulic fluid to a pressure set point. This allowscontrol valve 418 to reduce the hydraulic pressure in hydraulic circuit400 during an over-pressure condition and increase the pressure duringan under-pressure condition. Changes in pressure can be caused by, forexample but not by limitation, changes in temperature, etc.

Hydraulic circuit 400 can also include a manual valve 419 and/or apressure relief valve 421. In one example, manual valve 419 comprises aneedle valve that is manually operated to open and close conduit 408.Pressure relief valve 421 is configured to open and close in response tothreshold pressure events, such as the pressure in conduit 408 reachinga threshold level.

FIG. 4 shows that hydraulic circuit 400 includes a flow restrictingfeature 422, through which hydraulic fluid flow is controlled by controlvalve 412. Feature 422 is disposed in parallel with a portion 424 of thefluid flow path along which control valve 412 is disposed, and isconfigured to restrict the flow of fluid through conduits 406 and 408.Accordingly, when control valve 412 is in the open position shown inFIG. 4, the hydraulic fluid flows between accumulator 404 and floatcylinder 410 substantially unrestricted. However, when control valve 412is in the closed position (moved to the right in FIG. 4), the fluid flowis forced through feature 422, resulting in a restricted flow betweenaccumulator 404 and float cylinder 410. As such, the pressure will notequalize between accumulator 404 and float cylinder 410 as quickly (dueto the restriction of feature 422).

In the example of FIG. 4, feature 422 comprises a fixed orifice (alsoreferred to as fixed orifice 422). Of course, other types of flowrestricting mechanisms can be utilized. Fixed orifice 422 has an orificeopening that is smaller than the conduit defined by tubes 406 and 408,on either side of orifice 422. Therefore, orifice 422 illustrativelyrestricts the flow of hydraulic fluid through conduits 406 and 408 by afixed amount. Further, it is noted that the size of orifice 422 can beselected to achieve different affects. That is, its physical side andrestrictive properties can be selected to achieve a desired performance.If the orifice is larger (with less flow restriction), than that systemwill tend to allow float cylinder 410 to move more quickly during alowering operation than smaller, more restrictive orifice sizes.

In the illustrated example, control valve 411 is configured to beactuated manually and/or automatically by a control system 430. Forexample, an operator 432 can use a suitable mechanism to controlhydraulic circuit 400 to lock the position of frame assembly 403 byclosing control valve 411 and isolating float cylinder 410 fromaccumulator 404. This may be done, for example but not by limitation,when the header is being raised to make a subsequent turn in a fieldbetween passes. Some examples are described in further detail below.

In one example, control system 430 includes hardware items (such asprocessors and associated memory, or other processing components) thatperform the associated functions. In addition, the system can becomprised of software that is loaded into a memory and is subsequentlyexecuted by a processor or server, or other computing component. Thesystem can also be comprised of different combinations of hardware,software, firmware, etc. These are only some examples of differentstructures that can be used to form control system 430. Other structurescan be used as well.

Control system 430 can detect operator inputs 434 that are provided byoperator 432 through operator interface mechanism(s) 436. Control system430 can also detect sensor input(s) 438 that are provided from one ormore various sensors 440. For instance, control system 430 canautomatically detect when the header is being raised, or is about to beraised of the ground during a lifting operation. Control system 430 canreceive other inputs 442 as well. Control system 430 can then actuatecontrol valve 411 between the open and closed positions shown in FIGS. 4and 5, respectively, based on one or more of those inputs. This can bedone in a wide variety of different ways, and a number of examples willnow be described.

In one example, when the operator is providing an input to raise theheader, control system 430 can detect that operator input and not onlycontrol the lift actuator that is lifting the header, but it can alsocontrol the valve 411 to close it up, so that the fluid flow from floatcylinder 410 to accumulator 404 is isolated, thereby locking theposition of frame assembly 403.

Control valve 412 is actuated between the open and closed positionsbased on the respective fluid pressures in accumulator 404 and floatcylinder 410. As shown in FIG. 4, a first tube 424 is coupled to conduit406 and exposes a first side of control valve 412 to the fluid pressurein conduit 406. Similarly, a tube 426 receives fluid from conduit 408,which is exposed to an opposing side of control valve 412. Accordingly,differences in fluid pressure in conduits 406 and 408 automaticallyactuate control valve 412.

In one example shown in FIG. 4, control valve 412 is biased to the openposition by a biasing mechanism 428, such as a spring or other suitablemechanism. Biasing mechanism 428 applies a predefined amount of forceagainst control valve 412, to bias it to the open position. This definesa pressure differential that the pressure in fluid conduit 408 mustexceed (relative to the pressure in conduit 406) before control valve412 is moved to the closed position.

FIG. 5 illustrates an example method 500 of operation of hydrauliccircuit 400. For sake of illustration, but not by limitation, method 500will be described in the context of a lifting operation that lifts aheader assembly, and a subsequent lowering operation in which frameassembly 403 (e.g., wing section 204) is released. FIGS. 6 and 7illustrate operation of hydraulic circuitry 400 in conjunction withexample method 500.

Method 500 is performed during a harvesting operation, for example. Thisis represented by block 502. Accordingly, frame assemblies 403 and 405(e.g., wing section 204 and center section 202) are in aground-following configuration during a pass of over a terrain.

At block 504, a lifting operation is detected, in which the header islifted off the ground, for example in preparation of a turn to make asubsequent (e.g., parallel) pass over the terrain. This liftingoperation can be based on a user input (block 506), or automatic bycontrol circuitry of the harvesting machine.

At block 510, before the header is lifted off the ground, a lockingvalve is closed to lock the position of frame assembly 403 (e.g., wingsection 204) relative to frame assembly 405 (e.g., center section 202).In this regard, control valve 411 is actuated from the open positionshown in FIG. 4, to the closed position shown in FIG. 6. Closing ofvalve 411 isolates float cylinder 410 from accumulator 404, as discussedabove. This can be done in response to a user input (block 512) orautomatically (block 514) by control system 430 detecting that thelifting operation is to be performed.

At block 516, the header is lifted off the ground, with the frameassembly 403 in the locked position relative to frame assembly 405.Since the ground is no longer supporting frame assembly 403, thepressure in float cylinder 410 (and thus conduit 408) increasessignificantly, due to the weight of frame assembly 403 on rod 414.

For sake of illustration, but not by limitation, assume that prior toclosing the locking valve at block 510, the pressure in conduit 408 isapproximately 1900 pounds per square inch (psi). Because valve 411 isopen, the pressure in accumulator 404 and conduit 406 is alsoapproximately 1900 psi. However, when valve 411 is closed at block 510and the header is then lifted at block 516, the pressure in floatcylinder 410 and conduit 408 increases to approximately 3000 psi, whilethe pressure in accumulator 404 and conduit 406 remains at approximately1900 psi.

Due to this increase in pressure in conduit 408, the pressure in tube426 increases relative to the pressure in tube 424, beyond the pressureset point of biasing mechanism 428. In other words, the pressure inconduit 408 is great enough to overcome the fluid pressure in conduit406 and the force applied by biasing mechanism 428 on valve 412, whichcauses valve 412 to actuate to the closed position as shown in FIG. 7.In this closed position, flow through conduit 424 is blocked.

Once the header is positioned to make the subsequent pass, the header islowered at block 518. Ground contact is detected at block 520. Forinstance, control system 530 (or some other component of the machine)detects that the frame assembly 405 (e.g., center section 202) hascontacted the ground. In one particular example, this can be done bydetecting a location of the attachment frame, that attaches the headerto the traction unit, relative to an end stop. For example, groundcontact can be detected when the attachment frame has been raised athreshold amount (e.g., ten percent of the overall travel) off a bottomstop that holds the attachment frame when it is in the raise position.

At block 522, in response to detecting the ground contact at block 520,control valve 411 is opened to release frame assembly 403 from itslocked position relative to frame assembly 405. However, because controlvalve 412 has been actuated to its close position due to the increasedpressure in conduit 408, and control valve 411 is now open, fluid isallowed to flow from float cylinder 410 to accumulator 404 throughrestricting orifice 422. This flow is represented by arrows 524. Thisrestricted flow causes float cylinder 410 to retract more slowly,resulting in a damped lowering of frame assembly 403 to the ground. Oncethe flow through restricting orifice 422 lowers the pressure in conduit408 to a threshold pressure (corresponding to the pressure in conduit406 and force of biasing mechanism 428), control valve 412 automaticallymoves back to its open position in which fluid flow between floatcylinder 410 and accumulator 404 is substantially unrestricted.

Example 1 is a header assembly for an agricultural harvesting machine,the header assembly comprising:

a first frame assembly;

a second frame assembly that supports a cutter, and is pivotablerelative to the first frame assembly;

a float cylinder coupled between the first frame assembly and the secondframe assembly;

an accumulator; and

fluidic circuitry that fluidically couples the accumulator to the floatcylinder, wherein the fluidic circuitry is configured to:

-   -   provide a first flow of pressurized fluid under pressure to the        float cylinder, so the float cylinder exerts a float force on        the second frame assembly; and    -   based on a control input that corresponds to a lowering        operation of the header assembly, provide a restricted flow of        fluid, that is restricted relative to the first flow, between        the float cylinder and the accumulator.

Example 2 is the header assembly of any or all previous examples,wherein the lowering operation comprises a release operation thatreleases the second frame assembly from a locked position relative tothe first frame assembly to an unlocked position in which the secondframe assembly is in a ground-following configuration.

Example 3 is the header assembly of any or all previous examples,wherein the header assembly comprises a draper platform, the first frameassembly comprises a center section, and the second frame assemblycomprises a wing section that is pivotably supported by the centersection.

Example 4 is the header assembly of any or all previous examples,wherein the center section is coupled to an attachment frame that issupported by a traction unit of the agricultural harvesting machine, andthe lowering operation comprises the traction unit lowering the centersection from an elevated position above the ground to a ground-engagingposition.

Example 5 is the header assembly of any or all previous examples,wherein the fluidic circuitry comprises:

a fluid conduit defined by a tube that provides the pressurized fluid tothe float cylinder; and

a valve mechanism that is disposed in the fluid conduit and configuredto control flow of the pressurized fluid through the fluid conduit,wherein the valve mechanism is actuated by changes in fluid pressure inthe fluid conduit between:

-   -   a first position that allows the first flow of pressurized fluid        through the valve mechanism, and    -   a second position that inhibits fluid flow through the valve        mechanism.

Example 6 is the header assembly of any or all previous examples,wherein the fluid conduit comprises a first fluid conduit configured toprovide the first flow of pressurized fluid when the valve mechanism isin the first position, and the fluidic circuitry comprises:

a second fluid conduit having a flow restricting feature that isdisposed in parallel with the valve mechanism and configured to providethe restricted flow between the float cylinder and the accumulator whenthe valve mechanism is in the second position.

Example 7 is the header assembly of any or all previous examples,wherein the flow restricting feature comprises a flow restrictingorifice in the second fluid conduit.

Example 8 is the header assembly of any or all previous examples,wherein the flow restricting orifice defines an orifice opening that issmaller than the first fluid conduit.

Example 9 is the header assembly of any or all previous examples,wherein the valve mechanism comprises a first valve mechanism, and thefluidic circuitry comprises:

a second valve mechanism that is actuatable between an open positionthat fluidically couples the float cylinder to the accumulator and aclosed position that fluidically isolates the float cylinder from theaccumulator.

Example 10 is the header assembly of any or all previous examples,wherein the control input actuates the second valve mechanism from theclosed position, in which fluid flow from the float cylinder to theaccumulator is blocked, and the open position, in which the restrictedflow is provided through the flow restricting feature.

Example 11 is the header assembly of any or all previous examples,wherein fluidic isolation of the float cylinder from the accumulatorlocks the second frame assembly relative to the first frame assembly.

Example 12 is the header assembly of any or all previous examples, andfurther comprising:

a control system configured to generate the control input that releasesthe second frame assembly from a locked position relative to the firstframe assembly.

Example 13 is the header assembly of any or all previous examples,wherein the control input is generated based on an operator input.

Example 14 is the header assembly of any or all previous examples,wherein the control input is generated based on a sensed direction ofmovement of the header assembly.

Example 15 is a float force assembly for a harvesting machine header,the float force assembly comprising:

an accumulator; and

fluidic circuitry that fluidically couples the accumulator to a floatcylinder coupled between a first frame assembly of the harvestingmachine header and a second frame assembly that is movable relative tothe first frame assembly, wherein the fluidic circuitry comprises:

a valve mechanism that is actuatable between a first position and asecond position based on a pressure differential between the floatcylinder and the accumulator, wherein

-   -   when the valve mechanism is in the first position, the fluidic        circuitry provides a first flow of pressurized fluid under        pressure to the float cylinder, so the float cylinder exerts a        float force on the second frame assembly; and    -   when the valve mechanism is in the second position, the fluidic        circuitry provides a restricted flow of fluid, that is        restricted relative to the first flow, between the float        cylinder and the accumulator.

Example 16 is the float force assembly of any or all previous examples,wherein the second frame assembly comprises a wing section that ispivotably coupled to the first frame assembly.

Example 17 is the float force assembly of any or all previous examples,wherein the fluidic circuitry comprises:

a first fluid conduit that is controlled by the valve mechanism; and

a second fluid conduit disposed in parallel with the first fluid conduitand having a flow restricting feature configured to provide therestricted flow between the float cylinder and the accumulator when thevalve mechanism is in the second position.

Example 18 is the float force assembly of any or all previous examples,wherein the flow restricting feature comprises a flow restrictingorifice in the second fluid conduit, the flow restricting orificedefining an orifice opening that is smaller than the first fluidconduit.

Example 19 is the float force assembly of any or all previous examples,and further comprising a second valve mechanism that is actuatable tohydraulically isolate the float cylinder from the accumulator.

Example 20 is a header for a harvesting machine, the header comprising:

a main frame assembly;

a wing frame assembly pivotably coupled to the main frame assembly;

a float cylinder coupled between the main frame assembly and the wingframe assembly;

an accumulator; and

fluidic circuitry that fluidically couples the accumulator to the floatcylinder, wherein the fluidic circuitry comprises:

a valve mechanism that is actuatable between a first position and asecond position based on a pressure differential between the floatcylinder and the accumulator, wherein

-   -   when the valve mechanism is in the first position, the fluidic        circuitry provides a first flow of pressurized fluid under        pressure to the float cylinder, so the float cylinder exerts a        float force on the wing frame assembly; and    -   when the valve mechanism is in the second position, the fluidic        circuitry provides a restricted flow of fluid, that is        restricted relative to the first flow, between the float        cylinder and the accumulator.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A header assembly for an agricultural harvestingmachine, the header assembly comprising: a first frame assembly; asecond frame assembly that supports a cutter, and is pivotable relativeto the first frame assembly; a float cylinder coupled between the firstframe assembly and the second frame assembly; an accumulator; andfluidic circuitry that fluidically couples the accumulator to the floatcylinder, wherein the fluidic circuitry is configured to: provide afirst flow of pressurized fluid under pressure to the float cylinder, sothe float cylinder exerts a float force on the second frame assembly;and based on a control input that corresponds to a lowering operation ofthe header assembly, provide a restricted flow of fluid, that isrestricted relative to the first flow, between the float cylinder andthe accumulator.
 2. The header assembly of claim 1, wherein the loweringoperation comprises a release operation that releases the second frameassembly from a locked position relative to the first frame assembly toan unlocked position in which the second frame assembly is in aground-following configuration.
 3. The header assembly of claim 2,wherein the header assembly comprises a draper platform, the first frameassembly comprises a center section, and the second frame assemblycomprises a wing section that is pivotably supported by the centersection.
 4. The header assembly of claim 3, wherein the center sectionis coupled to an attachment frame that is supported by a traction unitof the agricultural harvesting machine, and the lowering operationcomprises the traction unit lowering the center section from an elevatedposition above the ground to a ground-engaging position.
 5. The headerassembly of claim 1, wherein the fluidic circuitry comprises: a fluidconduit defined by a tube that provides the pressurized fluid to thefloat cylinder; and a valve mechanism that is disposed in the fluidconduit and configured to control flow of the pressurized fluid throughthe fluid conduit, wherein the valve mechanism is actuated by changes influid pressure in the fluid conduit between: a first position thatallows the first flow of pressurized fluid through the valve mechanism,and a second position that inhibits fluid flow through the valvemechanism.
 6. The header assembly of claim 5, wherein the fluid conduitcomprises a first fluid conduit configured to provide the first flow ofpressurized fluid when the valve mechanism is in the first position, andthe fluidic circuitry comprises: a second fluid conduit having a flowrestricting feature that is disposed in parallel with the valvemechanism and configured to provide the restricted flow between thefloat cylinder and the accumulator when the valve mechanism is in thesecond position.
 7. The header assembly of claim 6, wherein the flowrestricting feature comprises a flow restricting orifice in the secondfluid conduit.
 8. The header assembly of claim 7, wherein the flowrestricting orifice defines an orifice opening that is smaller than thefirst fluid conduit.
 9. The header assembly of claim 6, wherein thevalve mechanism comprises a first valve mechanism, and the fluidiccircuitry comprises: a second valve mechanism that is actuatable betweenan open position that fluidically couples the float cylinder to theaccumulator and a closed position that fluidically isolates the floatcylinder from the accumulator.
 10. The header assembly of claim 9,wherein the control input actuates the second valve mechanism from theclosed position, in which fluid flow from the float cylinder to theaccumulator is blocked, and the open position, in which the restrictedflow is provided through the flow restricting feature.
 11. The headerassembly of claim 9, wherein fluidic isolation of the float cylinderfrom the accumulator locks the second frame assembly relative to thefirst frame assembly.
 12. The header assembly of claim 11, and furthercomprising: a control system configured to generate the control inputthat releases the second frame assembly from a locked position relativeto the first frame assembly.
 13. The header assembly of claim 12,wherein the control input is generated based on an operator input. 14.The header assembly of claim 12, wherein the control input is generatedbased on a sensed direction of movement of the header assembly.
 15. Afloat force assembly for a harvesting machine header, the float forceassembly comprising: an accumulator; and fluidic circuitry thatfluidically couples the accumulator to a float cylinder coupled betweena first frame assembly of the harvesting machine header and a secondframe assembly that is movable relative to the first frame assembly,wherein the fluidic circuitry comprises: a valve mechanism that isactuatable between a first position and a second position based on apressure differential between the float cylinder and the accumulator,wherein when the valve mechanism is in the first position, the fluidiccircuitry provides a first flow of pressurized fluid under pressure tothe float cylinder, so the float cylinder exerts a float force on thesecond frame assembly; and when the valve mechanism is in the secondposition, the fluidic circuitry provides a restricted flow of fluid,that is restricted relative to the first flow, between the floatcylinder and the accumulator.
 16. The float force assembly of claim 15,wherein the second frame assembly comprises a wing section that ispivotably coupled to the first frame assembly.
 17. The float forceassembly of claim 15, wherein the fluidic circuitry comprises: a firstfluid conduit that is controlled by the valve mechanism; and a secondfluid conduit disposed in parallel with the first fluid conduit andhaving a flow restricting feature configured to provide the restrictedflow between the float cylinder and the accumulator when the valvemechanism is in the second position.
 18. The float force assembly ofclaim 17, wherein the flow restricting feature comprises a flowrestricting orifice in the second fluid conduit, the flow restrictingorifice defining an orifice opening that is smaller than the first fluidconduit.
 19. The float force assembly of claim 17, and furthercomprising a second valve mechanism that is actuatable to hydraulicallyisolate the float cylinder from the accumulator.
 20. A header for aharvesting machine, the header comprising: a main frame assembly; a wingframe assembly pivotably coupled to the main frame assembly; a floatcylinder coupled between the main frame assembly and the wing frameassembly; an accumulator; and fluidic circuitry that fluidically couplesthe accumulator to the float cylinder, wherein the fluidic circuitrycomprises: a valve mechanism that is actuatable between a first positionand a second position based on a pressure differential between the floatcylinder and the accumulator, wherein when the valve mechanism is in thefirst position, the fluidic circuitry provides a first flow ofpressurized fluid under pressure to the float cylinder, so the floatcylinder exerts a float force on the wing frame assembly; and when thevalve mechanism is in the second position, the fluidic circuitryprovides a restricted flow of fluid, that is restricted relative to thefirst flow, between the float cylinder and the accumulator.